1. Field of the Invention
The invention is concerned with the art of controllably quench hardening work pieces such as crankshafts and the like.
2. Prior Art
Prior art die quenching equipment has generally consisted of a pair of platens which are vertically displaced from one another. In such apparatus a work piece such as a crankshaft or the like has generally been placed on the lower platen and supported thereby and then the upper platen has been propelled towards the lower platen to form a chamber about the crankshaft whereupon quenching has proceeded as by spraying liquid or the like on to portions of the work piece which are to be made especially hard. Generally, a flood of quench liquid has been added to the chamber shortly after the spraying of the quench liquid has begun. Typical die quenching apparatus and methods operating generally as described above are described in considerably more detail in each of U.S. Pat. Nos. 3,447,547; 3,506,501; 3,589,697; and 3,854,707. The latter patent is particularly concerned with inductively heating and quench hardening the bearing surface of a crankshaft.
A serious problem has existed with prior art apparatus and methods for die quenching of work pieces. In particular, when the work piece is placed upon the lower platen of two vertically separated platens it immediately begins to slowly cool at its points of contact with the lower platen. While the degree of pre-cooling can be minimized as taught for example in U.S. Pat. Nos. 3,506,501 and 3,589,697 it has been found that the obtaining of a uniform hardened bearing surface on a work piece is generally deleteriously affected by its sitting upon the lower platen. This can lead to soft spots and/or distortion of the work piece under heavy load conditions.
The present invention provides a solution to the above-mentioned problem. In particular, the present invention provides a die quench apparatus and method wherein horizontally separated vertical platens replace the prior art vertically separated horizontal platens and where, hence, the work piece never sits upon a lower platen. Even more particular, the work piece never sits for any even slightly extended length of time against any platen before quenching is begun.